Objective:To assess the correlation of transcutaneous oxygen pressure（PctO

2

）and partial pressure of oxygen in arterial blood（PaO

2

）

transcutaneous carbon dioxide pressure（PctCO

2

）and partial pressure of carbon dioxide in arterial blood（PaCO

2

）under different circulation states and to know the significance of PctO

2

/PctCO

2

under micro-circulatory disorder. Methods:Totally 110 sampling of PctO

2

/PctCO

2

and arterial blood gases（ABG）from November 2014 to March 2015 in 56 cases were collected;the correlation and difference between PctO

2

and PaO

2

PctCO

2

and PaCO

2

under different circulation states were analyzed and the sensitivity and specificity of oxygen and carbon dioxide retention by PctO

2

and PctCO

2

under ROC curve were evaluated. Results:In the normal microcirculation group（n=75）

PctO

2

and PaO

2

PctCO

2

and PaCO

2

were in good correlation（r=0.937

0.569

P

<

0.05）. In the mildly and seriously micro-circulation disorder group（n=20

15）

PctCO

2

and PaCO

2

were in good correlation（r=0.718

0.679

P

<

0.05）;PctO

2

had no relation with PaO

2

（P=0.175

0.074）. The △PO2（PaO

2

-PctO

2

）in the normal micro-circulation group（n=75）

the mildly micro-circulation disorder group（n=20）and the seriously microcirculation disorder group（n=15）were（0.24 ±1.08）

（7.99 ±7.99）

（9.71±5.15）k Pa respectively. In the normal micro-circulation group（n=75）

the AUC of PctO

2

was 0.89（95%CI=0.82 to 0.96

P=0.036）. PctO

2

can predict hypoxia with the optimal threshold value given by ROC analysis at 10.25 k Pa（Sen:81.5%

Spe:83.3%）. The AUC of PctCO

2

was 0.77（95%CI=0.65 to 0.88

P=0.000）. PctCO

2

can predictCO

2

retention with the optimal threshold value given by ROC analysis at 5.45 k Pa（Sen:81.5%

Spe:66.7%）. Conclusion:In the normal micro-circulation

PctO

2

/PctCO

2

monitoring can predict the PaO

2

/PctCO

2

to some degree. Under the mildly and seriously micro-circulation disorder

PctCO

2

can predict the PctCO

2

to some degree. The obvious difference between PctO

2

and PaO

2

suggests poor micro-circulation perfusion

therefore

PctO

2

/PctCO

2

monitoring combined with PaO

2

/PaCO

2

is needed for critically ill patients who need ABG.